Thermostatic regulator



Oct. l5, 1929. A. J. MoTTLAu 1,731,903

THERIOSTATIC REGULATOR Original Filed April 8, 1924 Fig. 1. 1I

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' v v ATTORNEY Patented oa. 15, 'i929 UNITED STATES PATENT OFFICE AUGUST I. IIOTTLAU, or PITTSBUPCII, PENNSYLVANIA, AssIGNOa To wnsTINaIIOUsn` ELECTRIC a MANUFACTURING COMPANY, A CORPORATION or PENNSYLVANIA TBERNDSTA'JTIC` REGULATOR Application led April 8, 1924, Serial No. 704,989. Renewed ctober`25, 1926;

My invention relates to 'temperature reprovide a thermostatic regulator thatshall be particularly adapted for insertion into domestic appliances (wherein the saving of space is a material consideration. f'

Another object OI' my Iinvention is to provide a thermostatic regulator that shall be capable of adjustment without the addition.

of externaldetails that would increase the overall dimensions thereof.

In the accompanying drawings,v4 Figure 1 is an enlarged elevational view of a thermostatic regulator embodying my invention,

Fig. 2 is a sectional view thereof taken lalong the section line II-II of Fig. 1, and

Fig. 3 is a sectional view of a detail thereof taken along the section line III-, III of Fig. 1.

My .invention comprises, in general, a frame 1 that yieldingly supports a pre-shaped spring 2 that controls aA circuit comprising contact members 4 that are supported on the frame 1. i

The frame 1 comprises a strip of U-shape and composed of materials 5 and 6 having Adiferent'thermal co-eilicients of expansion.

The material 5, which may be brass, should have a higher thermal co-etlicient of expanthe frame.

sion than the materlal 6, which may be invar steel, and should be placed on the outer side of With this disposition of parts, when the frame 1 is subjected to increase in temperature, the upper ends of the frame 1 will be caused to move inwardly by reason of the greater expansion of the strip 5 than of the strip 6.

' A bracing member 7 is secured by rivets 8 or by other well known means to-the central portion4 ofthe base section of the frame 1, audit extends upwardly slightly beyond the free ends of the frame 1. The up-turned end 9 of the brace 7 supports an adjusting screw 11 for a purpose to be hereinafter scribed..

Referring to Fig. 2, the brace 7 does not extend laterally beyond the width of ,the

frame 1. From an axis at substantially twothirds of the length of the brace 7, projecting arms 12 and 13 extend outwardly terminating in` lingers 14 and 15, between which are fitted the freely moving ends of the frame member 1. An adjusting screw 16 isfitted vto one of the fingers 15 for a` purpose to be hereinafter descrlbed. The shape of the entire brace member 7 is substantially that of a cross with the ends of the arms thereof bent at right angles to the body portion, in the lsame direction and for ,a distance not ex. ceedingr the width of the base member 1.

A block vof insulatingl material 17 is adljustably secured by a screw 18 passing through insulating block 17 carries the contact members 4 that are controlled by adjusting screws 20, The insulating block 17, the contact members 4 and the adjusting screws 20 may be removed from the bracing member 7, as a unit, by simply manipulating the adjusting screw 18.

The spring 2 constitutes a movable Contact a slot 19 therein to the brace 7. The

member cooperating with the stationary contact members 4 and it extends between bushings 21 inserted near the respective free ends of the frame 1. The initial shape of the spring 2 is a very important feature of the present invention. Referring to Fig. 1, vthe spring is bent upwardly, as at 22,'for a short distance from t e bushings 21, and then the spring is bentv sharply downwardly tothe points '23, Tlf/he total distance included by the curved portions 22 and 23 is small when compared with the section 24 connecting the portions 23. By reason of this configuration of the ends of the springs, initial pressure applied longitudinally of the spring 2 causes the portions 23 to move downwardly and Increase the pressure of these portions against the stationary contact members 4. This is a very important feature of the present invening between the spring 2 and the stationary contact members 4 when the thermostatic regulator is very near its operating temperature. l i i The bushings 21 are cylindrical in form and their diameters do not exceed the width of the frame member 1. The bushings are provided with V-shaped notches 25 for the reception ofthe ends of the spring 2. The bushings 21 may be composed of an insulating material commonly known as ,fmoulded lava.7 They are also provided with shanks 26 that extend through suitable openings in the frame 1.

The Shanks 26 may be circular or of rectangu-` lar cross section, as desired. A

The spring 2 is providedwith tail-pieces 27 that extend through openings 28 in the bushings 21 and shanks 26. The tail-pieces 27 prevent the spring 2 from being dislocated relative to the frame 1. ,The bushings 21 may be renewed if the thermostat becomes inaccurate by reason of the wearing away of the material thereof at their points of engagement with the spring 2. p I

In the operation of my thermostatic regulator, the adjustment screw 16 is so set thatit 'bearsagainst one of the end sections of the frame 1. I have found that a singe adjustment screw 16 is sufficient to calibratethej 'regulatoryalthough one may be employed at each/end of the frame, if desired. The adjustment screws 20 are then set so that the stationary contact members 4 bear against 'the'portions 23 of the spring 2 at normal operating temperature. The adjustment screw 11 is then set to provide an upper limit to the travel of the spring 2 as hereinafter described. The location of the stationary contact members 4\is roughly found by manipulation of 'the set screw'18 and the finer adjustments are Upon an increase in temperature; of the thermostatic regulator, the outer strip 5 there/of expands at a greater ratethan vthe inner strip 6, to cause the free ends of the frame 1 to move inwardly and impress a longitudinal compressive force on the spring2.-

Initial movement of the springY 2 causes the portions 23 to bear more firmly upon the stationary contact members4 as heretofore described, while the central section 24 tends to bow upwardly. `Continued longitudinal pressure on the spring 2 causes thel section 24 to continue'itsoutward movement until astate of unstable equilibrium is reached at which the entire spring 2 moves upwardly orl outl wardly against the screw 11 with a snap action.' This snap. action (serves to interrupt a circuit comprising the stationary contact members 4 and the-spring 2. The outward position of the springs 2 is shown in broken lines in Fig. 1. i I j Upon the coolingiofthe frame 1 to a predetermined temperature, the ends move outwardly and diminish the compression of the -tween the supports, the

members 4. This cycle of operations may be 1 continued indefinitely.

It will thus be seen that I have provided a thermostat-ic 'regulator that is characterized by having a frame ofl bimetallic material operatinfr a pre-shaped spring for the purpose of ma ring and breaking an electric circuit. My thermostatic regulator is also characterized by the fact that all\`of.the operating parts are confined in a space, the widthof which is approximately that of the width of the frame therefor, and that projecting adjusting features havebeenlargely eliminated. The shape of the spring is such that a firm engagement between it and the stationary contact members is maintained until the thermostatic regulator'operates to disengage the contact members. With my regulator an electric circuit maybe interrupted at a predetermined "temperature and reclosed at another lower predetermined temperature and the difference between these values may be adjusted to any desired value. s

I do not wish to be restricted to the specific circuit connectfonsor arrangement of parts herein set forth, as various modifications soY thereof may be eii'ected without departing v' fromthe spirit and scope of my invention. I desire therefore, that only such limitations shall be imposed as are indicated in' the appended claims.

I claim as my invention: g

1. Incombination,thermoresponsivemeans having a pair of supports, a stationary contact member, and a pre-shaped resilient member, comprising a main and two relatively shorter end portions having the same direc-` tion of curvature and connecting portions of sharp reverse curvature, mounted between the V.supports for engagementwith the stationary contact member in faccordance with ,the degree of energizati'on'of vthe thermoreysponsive means. "l

2. In combination, thermoresp onsive means having a pair/of supports, a pair of stationary contact members, .and a pre-shaped resilient member, comprising a main and two shorter 'end portions having the same direction of curvature and connectingportions of sharp reversei curvature, mounted `be.- ortions of reverse curvature engaging thecontact members in accordance with the degree of energizati'on of the thermoresponsive means.

3. In^combination,thermoresponsivemeans having a pair of supports, a pair of stationary l'contact members,.and a pre-shaped resilient member, having a main and two" shorter end portions of .the same direction of curvature and connecting portions ofsharp reverse curvature, mounted betweenthe sup-'` ports, the portions of reverse. curvature encontact members until the main portion buckles to thereby disengage the Stationary contact members with a snap action.

4. Incombination,thermoresponsivemeans having a pair of supports, a pair of stationi ary contact memberswand a prke-shapedresilient member, having a main and twoy end portions of the same direction of curvature and connecting portions of reverse curvature, mounted between the supports, the portions of reverse curvature engagingthe contact members in accordance with the degree of energization of the thermoresponsive means, initial longitudinal pressure on the resilient member causing the portions of reverse curvature to firmly engage the stationary contact members until the main portion buckles therebyVA disengaging the reversely curved portions from the stationary contact members with a snap'action, said resilient member returning to its original position upon the reduction of the longitudinal pressure;

5. .In combination, a flexible base member having a pair o'f supports, a pair of stationary contact members, and a pre-shaped resilient member, having a main and two shorter end portions of the same direction of curvature and connecting portions of sharp reverse curvature, mounted between the supports, the portions of reversecurvature engaging the contact members in accordance with the degree of lexure of the base member. v

6. In combination,thermoresponsive'means `havinga pair' of supports, a pair of stationary contact members, and a pre-'shaped resilient member having a main and two shorter end portions of the same direction of'curvature and connecting portions'of sharp reverse curvature, mounted between the supports( the portions of reverse curvature engaging the" contact members in ,accordance with the degree of energization of the thermoresponsive means, initial longitudinal pressure on the resilient member causin the portions of reverse curva-ture to iirm yengage 'the stationary contact members until `the main portion buckles. thereby disengaging the portions of reversed curvature` fromV thel stationarycontact members with. a snap ac-I tion.

7. Incombination,thermoresponsivemeans, cooperating supporting means, a pair of stationary contact members, 'and a preshaped resilient member-having amain portion, two end portions of the same direction of curvature and connecting portions of rev erse curvature mounted between the supports, .the portions of reversel curvature engaging the contactmembers in accordance with the degree of energization ofthe thermoresponsive means, initial longitudinal pressure on the resilient member causing the portions of reverse curvature to firmly engage the stationary contact members until the main portion buckles thereby disengaging the stationary contact members with a snap action, said resilient member returning to its original position upon the reduction of the longitudinalv pressure.

8. In a switch tact member, a resilient'member having portions of the same directiomof curvature and a connecting portion of reversed curvature, the portion of reverse curvature engaging the stationary contact member, and means for imparting a longitudinal thrust to the resilient member whereby engagement between the stationary contact member and the portion ofreverse curvature is maintained until one of the curved portionsbuckles in a direction op'posite'tothe stationary contact member with an accompanying abrupt 'disengagement between the stationary contact member and the portion of sharp curvature.

9. `A thermal switch comprising a stationary contact member, a single return-bent bimetallic member, and a resilient member longitudinally disposed between the ends thereof, said resilient member being of substantially sinuous shape and adaptedto defleet laterally between its ends with a snap motion when subjected to a longitudinal pressure and to retrace said'deflection upon the removal of said pressure, said bimetallic member being adapted to exert a longitudinal pressure on' the resilient member in accordance with. the temperature to which` it is subjected.

10. A thermal switch comprising a returnbent bimetallic member, anda resilient memstructure, a stationary con-Y ber, having an end portion thereof deformed laterally of its length, disposed between the ends-of the bimetallic member,said resilient member being adapted to deflect laterally of its length with a snap motion when subject-.

and to automatically retrace said deflection with al snap motion upon the removal of said pressure g 12. In combination, a bimetallic ralm of substantially U-shape, a pre-shaped resilient member supported by and between the ends Q of vthe frame, a bracing member supported bythe frame at its intermediate portion,` said bracing member embodying stop members for limiting the movement of the ends of the bimetallic frame, and Contact members sup-l, ported by said bracing member and cooper- 5 ating with the pre-shaped resilient member.

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In testimony whereof, I have hereunbosubscribed my name this 28th day of March,

AUGUST J. MOTTLAU. 

